1. Field of the Invention
The invention relates to an everter and threadthrough device for attaching a graft vessel to an anastomosis device which can be used for forming a sutureless connection between a bypass graft and a blood vessel.
2. Brief Description of the Related Art
Vascular anastomosis is a procedure by which two blood vessels within a patient are surgically joined together. Vascular anastomosis is performed during treatment of a variety of conditions including coronary artery disease, diseases of the great and peripheral vessels, organ transplantation, and trauma. In coronary artery disease (CAD) an occlusion or stenosis in a coronary artery interferes with blood flow to the heart muscle. Treatment of CAD involves the grafting of a vessel in the form of a prosthesis or harvested artery or vein to reroute blood flow around the occlusion and restore adequate blood flow to the heart muscle. This treatment is known as coronary artery bypass grafting (CABG).
In the conventional CABG, a large incision is made in the chest and the sternum is sawed in half to allow access to the heart. In addition, a heart lung machine is used to circulate the patients blood so that the heart can be stopped and the anastomosis can be performed. During this procedure, the aorta is clamped which can lead to trauma of the aortic tissue and/or dislodge plaque emboli, both of which increase the likelihood of neurological complications. In order to minimize the trauma to the patient induced by conventional CABG, less invasive techniques have been developed in which the surgery is performed through small incisions in the patients chest with the aid of visualizing scopes. Less invasive CABG can be performed on a beating or stopped heart and thus may avoid the need for cardiopulmonary bypass.
In both conventional and less invasive CABG procedures, the surgeon has to suture one end of the graft vessel to the coronary artery and the other end of the graft vessel to a blood supplying vein or artery. The suturing process is a time consuming and difficult procedure requiring a high level of surgical skill. In order to perform the suturing of the graft to the coronary artery and the blood supplying artery the surgeon must have relatively unobstructed access to the anastomosis site within the patient. In the less invasive surgical approaches, some of the major coronary arteries including the ascending aorta cannot be easily reached by the surgeon because of their location. This makes suturing either difficult or impossible for some coronary artery sites. In addition, some target vessels, such as heavily calcified coronary vessels, vessels having very small diameter, and previously bypassed vessels may make the suturing process difficult or impossible.
An additional problem with CABG is the formation of thrombi and atherosclerotic lesions at and around the grafted artery, which can result in the reoccurrence of ischemia. The thrombi and atherosclerotic lesions may be caused by the configuration of the sutured anastomosis site. For example, an abrupt edge at the anastomosis site may cause more stenosis than a more gradual transition.
Accordingly, it would be desirable to provide a sutureless vascular anastomosis device which easily connects a graft to a target vessel. It would also be desirable to provide a sutureless anastomosis device which is formed of one piece and is secured to the target vessel in a single step.
The invention provides an everter tool useful for everting an end of a graft vessel over an end of an anastomosis device. The everter tool preferably includes a mechanism which expands an end of a graft vessel and everts the end of the graft vessel over an anastomosis device mounted on a deployment tool. For instance, the mechanism can include a first member having fingers at a distal end thereof, the fingers being expandable from a first configuration which fits within the and of the graft vessel to a second configuration which expands the end of the graft vessel, and an optional second member cooperating with the first member such that the second member is movable from a first location at which the fingers are in the first configuration to a second location at which the second member expands the fingers to the second configuration.
The everter tool can include various features. For example, the everter tool can be slidably received in a bore of an everter fixture and a handle on the everter tool can be used to engage a first portion of the handle with the first member and a second portion of the handle with the second member, the handle being movable in an axial direction such that the second portion pushes the second member along the first member until a distal end of the second member expands the fingers from the first configuration to the second configuration after which the first portion pushes the first member along the bore until the fingers evert the graft vessel. In such a case, a deployment tool having an anastomosis device mounted on a distal end thereof and a graft vessel fitted through the anastomosis device can be located in the bore of the housing such that the fingers can be pushed into a portion of the graft vessel extending beyond an end of the anastomosis device.
In order to locate the graft vessel in the anastomosis device, a threadthrough device can be used for pulling the graft vessel through the anastomosis device. The threadthrough device can include a clamp which attaches to an end of the graft vessel and an extension attached to the clamp, the threadthrough device being sized to pass through the anastomosis device. The threadthrough device can also include a tongue pivotally connected to the clamp, the clamp being movable towards and away from the tongue such that the graft vessel can be clamped between the clamp and the tongue. In a preferred embodiment, the threadthrough device includes three clamps and the extension comprises a wire connected to each of the clamps.
According to a preferred embodiment, the anastomosis device includes barbs for penetrating the graft vessel and the everter tool includes a membrane engageable with the anastomosis device such that the barbs penetrate the graft vessel when the membrane is pressed against the anastomosis device.
The invention also provides a method of everting a graft vessel onto an anastomosis device, the method comprising locating a graft vessel in an anastomosis device mounted on a deployment tool such that a first portion of the graft vessel is within the deployment tool and a second portion of the graft vessel extends from an end of the deployment tool, expanding the second portion of the graft vessel, and everting the second portion of the graft vessel over the anastomosis device.
The method can be carried out in any suitable manner. For instance, the step of locating the graft vessel in the anastomosis device can be carried out by attaching an end of the graft vessel to a threadthrough device and passing the threadthrough device through the deployment tool. The step of expanding the second portion of the graft vessel can be carried out by inserting an everter tool into the second portion of the graft vessel. In such a case, the everter tool can optionally be pressed against the distal end of the deployment tool until barbs on a distal end of the anastomosis device penetrate the graft vessel. The step of expanding the second portion of the graft vessel can be carried out by inserting fingers of the everter tool into the second portion of the graft vessel and expanding the fingers within the second portion of the graft vessel. The step of everting the second portion of the graft vessel can be carried out by pressing the everter tool against the deployment tool. The step of expanding the second portion of the graft vessel can be carried out by locating the deployment tool in a bore of an everter fixture and sliding the everter tool from a first position to a second position along the bore. The step of everting the second portion of the graft vessel can be carried out by sliding the everter from the second position to a third position along the bore. The step of locating he graft vessel in the anastomosis device can be carried out by passing a threadthrough device through the deployment tool, the threadthrough device having a clamp attached to an end of the graft vessel and a wire extending from the clamp, the wire being pulled through an angled hole in the fixture while the graft vessel is pulled through the anastomosis device. In such a case, the clamp can be designed to spring open after passing out of the anastomosis device leaving a segment of the graft vessel extending beyond a distal end of the anastomosis device. According to a preferred embodiment, the step of everting the graft vessel can be carried out by pressing a first portion of the everter tool against an annular section of the graft vessel and moving a second portion of the everter tool in contact with an inner surface of the graft vessel until the inner surface is turned inside out over the anastomosis device.